/Engine/Plugins/Online/OnlineSubsystemUtils/Source/OnlineSubsystemUtils/Classes/OnlineSessionClient.h
Destroys an existing session of a given name
void DestroyExistingSession ( [FName](API\Runtime\Core\UObject\FName) SessionName, [FOnDestroySessionCompleteDelegate](API\Plugins\OnlineSubsystem\Interfaces\FOnDestroySessionCompleteDelegat-) & Delegate )